Divisible Sum Pairs Hackerrank Challenge: https://www.hackerrank.com/challenges/divisible-sum-pairs/problem?isFullScreen=true

divisibleSumPairs.js

function divisibleSumPairs(n, k, ar) {
    // Write your code here
    let counter = 0;
    for(let i = 0; i < n; i++) {
        for (let j = i+1; j < n; j++) {
           if ((ar[i]+ar[j]) % k === 0) counter++; 
        }  
    }
    return counter;

}